At least that’s what Pope Francis warned on Monday during an unusually stern lecture on the ills of pet ownership over parenthood.

The pontiff — celebrating Mass for 15 married couples in the chapel at the Santa Marta residence where he lives inside the Vatican — said couples who have pets rather than kids are doomed to the “bitterness of loneliness” in old age.

Francis told the couples, whose marriages ranged from 25 to 60 years, that he appreciates the freedom childless couples enjoy, but argued that it can last for only so long.

“You can go explore the world, go on vacation, you can have a villa in the countryside, you can be carefree,” the pope said, according to a report in the Religion News Service.

“It might be better — more comfortable — to have a dog, two cats, and the love goes to the two cats and the dog. Is this true or not? Have you seen it?”

He concluded: “Then, in the end this marriage comes to old age in solitude, with the bitterness of loneliness.”

The pope’s remarks come in light of recent birth-rate statistics out of Italy and the United States showing that more and more couples are putting off kids until later in life or altogether skipping parenthood.

Francis said raising children is the natural outcome of marriage.

“Married life must be persevering, because otherwise love cannot go forward,” Francis said.

“Perseverance in love, in good times and in difficult times, when there are problems: problems with the children, economic problems.”

He bluntly said Jesus Christ would not approve of a childless marriages.

Time magazine last year seemed to crystallize the issue with a huge spread on, “The Childfree Life,” which chronicled the personal choice of an increasing number of Americans to reject parenthood.

And in the pope’s own back yard, the Italian government reported last week that the overwhelmingly Catholic nation’s birth rate hit a record low of 515,000 in 2013. That’s a significant decline of 64,000, compared to the number of births as recently as 2008.